Computer systems often include an on-line documentation facility whereby various kinds of system information is made available to users in response to the issuance of documentation, or "help," commands. For example, a user might issue a documentation command such as HELP TERM=BILLING.sub.-- IDENTIFIER in response to which the system will provide documentation to the user at his or her terminal as to the meaning of the term "billing identifier" as it is used in the system. Or the user might issue a documentation command such as HELP COMMAND=CALL in response to which the system will provide documentation as to how the "call" command is to be used. Another possibility is a documentation command such as HELP ERROR=E.sub.-- NOT.sub.-- FOUND in response to which the system will provide documentation about the error whose mnemonic is E.sub.-- NOT.sub.-- FOUND.